[PATCH v3 2/7] SUNRPC: hold current network namespace while pipefs superblock is active

[Stanislav Kinsbursky <skinsbursky@parallels.com>]

We want to be sure that network namespace is still alive while we have pipefs
mounted.
This will be required later, when RPC pipefs will be mounting only from
user-space context.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>

---
 net/sunrpc/rpc_pipe.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index bb8a40b..ff41fef 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -27,6 +27,9 @@
 #include <linux/workqueue.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
 #include <linux/sunrpc/cache.h>
+#include <linux/nsproxy.h>
+
+#include "netns.h"
 
 static struct vfsmount *rpc_mnt __read_mostly;
 static int rpc_mount_count;
@@ -1012,6 +1015,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
 	}
 	if (rpc_populate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF, NULL))
 		return -ENOMEM;
+	sb->s_fs_info = get_net(net);
 	return 0;
 }
 
@@ -1022,11 +1026,19 @@ rpc_mount(struct file_system_type *fs_type,
 	return mount_ns(fs_type, flags, current->nsproxy->net_ns, rpc_fill_super);
 }
 
+void rpc_kill_sb(struct super_block *sb)
+{
+	struct net *net = sb->s_fs_info;
+
+	put_net(net);
+	kill_litter_super(sb);
+}
+
 static struct file_system_type rpc_pipe_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "rpc_pipefs",
 	.mount		= rpc_mount,
-	.kill_sb	= kill_litter_super,
+	.kill_sb	= rpc_kill_sb,
 };
 
 static void